Your project's running smoothly until someone checks the scaffolding invoice and realises it's triple the estimate. Poor management of preliminaries in construction bleeds budgets dry faster than most contractors expect, eating up 5% to 15% of total project value. Knowing what the preliminaries in construction and keeping them under control separates profitable contractors from those constantly chasing lost margins.
What Are Preliminaries in Construction?
Preliminaries cover every cost you need to get construction work done that can't be pinned to specific building components. The scaffolding holding up your bricklayers? That's a prelim cost. The bricks? Not prelims. Site manager's salary? Prelims. Subcontractor labour? Nope.
Think of it this way. Preliminaries are the operational backbone keeping actual construction moving. No temporary power means your tools don't run. No welfare facilities means workers can't legally occupy the site. No site security means your materials walk off overnight. These expenses keep everything functioning even though they produce nothing you can point at in the finished building.
UK construction contracts split preliminaries into two types that behave completely differently. Fixed preliminaries happen once regardless of how long your project takes. Time-related preliminaries accumulate throughout the programme. Run four months over schedule and watch your prelim budget get demolished. The permanent works scope hasn't changed one bit. Doesn't matter. Those weekly costs kept ticking.
| Type | Behaviour | Examples | Programme Impact |
|---|---|---|---|
| Fixed | One-off costs incurred regardless of duration | Site setup, mobilisation, permits, initial hoarding, temporary building connections | Stays constant if programme extends |
| Time-related | Accumulates weekly/monthly throughout project | Plant hire, site management salaries, welfare running costs, security, scaffolding hire | Increases directly with every delay |
Key Preliminary Categories to Address During Preconstruction
The preconstruction phase decides if your preliminary budget survives or collapses. Rush your estimates and you'll produce fictional numbers that fall apart under scrutiny. Thorough preconstruction planning identifies what you actually need before you've committed to anything.
Site Establishment and Temporary Services
Site establishment turns raw land into somewhere you can actually build. Access roads, site compounds, hoarding, welfare cabins, material storage, security fencing. Each item needs realistic pricing based on your specific site conditions. Generic allowances won't cut it. A tight urban plot with no laydown space costs more to establish than a greenfield site with room to spare.
Temporary services keep everything operational. Remote sites demand more investment in electrical connections, water supply, and telecoms. Urban sites cost less to service but might need traffic management plans and neighbour liaison programmes. Those generate their own preliminary expenses that catch contractors off guard.
Plant, Equipment, and Management
Plant and equipment serving the whole project belongs in preliminaries. Tower cranes working across multiple trades rack up substantial prelim costs every single week. Specialist kit hired for particular tasks goes into relevant work sections instead.
Management and supervision costs build up throughout delivery. Site managers, QSs, health and safety officers. Their salaries represent time-related expenses that grow whenever programmes extend. Preconstruction planning needs to assess management requirements based on actual project demands. Not just slapping on a percentage mark-up.
How Your Construction Phase Plan Affects Preliminary Costs

Your construction phase plan serves as the operational blueprint once work kicks off. Weak plans create coordination failures that inflate preliminary costs through delays, abortive work, and emergency interventions. Strong plans do the opposite by anticipating dependencies and building realistic allowances into your budget from the start.
Consider trade sequencing. Bricklayers need scaffolding. Mechanical contractors need the same scaffolding for external work. Proper coordination keeps it in place for both rather than striking and re-erecting. Poor sequencing forces repeated plant moves, extra supervision hours, wasted materials. Each one lands in your prelim budget. The same logic applies to tower crane usage, material deliveries, and subcontractor access.
Beyond sequencing, your construction phase plan must account for regulatory obligations that generate their own prelim costs. Health and safety arrangements require dedicated personnel, training programmes, monitoring systems, PPE provisions. CDM regulations don't care about your profit margins. Spell these requirements out clearly or your estimates reflect wishful thinking rather than actual obligations.
Weather adds another layer of preliminary exposure on any UK project. Winter working means additional lighting, heating, ground protection, drying-out allowances. These extend programmes, and every extra week on site inflates those time-related preliminaries you budgeted so carefully. A realistic construction phase plan accounts for seasonal conditions rather than assuming perfect weather year-round.
Building a Resource Management Plan That Protects Margins
Equipment and material control separates profitable contractors from those perpetually wondering where margins vanished. A proper resource management plan tracks everything entering and leaving site, assigns accountability, and prevents the gradual asset leakage that erodes project finances.
Without controls, construction sites descend into chaos. Tools end up scattered across multiple locations. Equipment gets borrowed and never comes back. Materials sit exposed to weather because nobody owns responsibility for proper storage. Consumables disappear faster than usage rates justify. Each failure represents a preventable preliminary cost increase that chips away at your margin.
The solution starts with clear custody protocols. Without them, accountability becomes impossible and losses stay invisible until the final account reveals the damage. Your resource management plan needs to establish who owns responsibility from the moment assets arrive on site until they leave.
An effective plan addresses five priorities:
- Delivery procedures specifying who receives goods, checks quantities, and signs off
- Storage assignments designating where each material type belongs and who maintains it
- Equipment checkout records tracking custody transfers between personnel
- Movement documentation logging when assets shift between locations or projects
- Condition reporting capturing damage or wear at each handover point
These protocols only work if you also address maintenance. Plant sitting idle awaiting repairs generates hire costs without any productive output. A £500 weekly hire charge doesn't pause while you wait for parts. Preventive maintenance schedules keep equipment running while breakdown response protocols minimise downtime when problems occur. Your resource management plan needs to specify both preventive and reactive procedures, because equipment availability directly affects your preliminary cost exposure.




